. >> reporter: john mccain and kerry forged close bonds over vietnam. both naval officers, mccain was imprisoned. kerry returned to testify against the war in 1971. his first appearance before this committee. >> how do you ask a man to be the last man to die in vietnam? >> reporter: decades later, they united as senators to resolve p.o.w. issues and normalize relations with vietnam. >> working toward that end with john and witnessing almost daily his exemplary statesmanship is one of the highest privileges i've had here. >> reporter: today, they do have differences. mccain is more willing to arm the rebels in syria. >> i think we ought to tell the syrian people that we're either going to help them or we're not. >> if you have a complete implosion of the state, nobody has clearer definition of how you put those pieces back together. >> reporter: he and others also pressed kerry on benghazi. >> are you willing to work with me or do you basically kind of agree hillary clinton that that's kind of yesterday's news and let's move on? >> well, senator, if you'